Capacity: 7 plastic cards, 1 driver’s License, 5 significantly aged business cards – seldom used but well protected, and several folded US bank notes.
Compact Wallet – Traceability Matrix
| User Requirements | Design Requirements | Vreification / Validation |
|---|---|---|
| Portability | Max Size: 95 x 61 x 20 mm (HT x W x Thk) | Inspection of first articles and production |
| Content Security | Lid must remain closed under 1G of force. | Shake test. User feedback |
| Nice Tactile Feedback | Snap retention must provide audible "click." | Acoustic Test. User feedback. |
| Longevity | Snap features must survive daily use and "fidget" cycles. | Simulated use and field testing |
| Easy access to contents | access specific item in > 10 secs | Access test. Use testing. User feedback |
Compact Wallet – DFMEA
| Feature/Function | Failure Mode | Effect of Failure | Cause | Mitigation |
|---|---|---|---|---|
| Lid Snap Retention | Fatigue Fracture | loose lid during transport | Too much flex of snap feature | Optimize geometry for flex and retention. Material: PETG |
| Easy Access of Contents | Lock out, can't retrieve contents | Cards stuck, user has to pinch to remove | Excessive friction, internal cavity | +1 mm clearence on standard CC |
| Ease of stowage and retrieval from tight pockets | Lock out, can't retrieve wallet | User frustration, delay of transactions | Excessive friction, external surface, Wallet size too big for pocket | Grip indents on sides, Wallet external dimensions |
A third critical document in product development is the V & V Test Plan, in some industries known as the DVPR – Design Validation Plan and Report.
Testing Feedback: I’ve been using the compact wallet for over a year. It requires some new coordination to access cards in the center of the stack as compared to a standard wallet where the items are splayed. The compact wallet resembles a deck of cards, making it necessary to partially remove the stack if a seldom used card is needed form the center. Although this activity requires a few extra seconds, it is a minor inconvenience that is outweighed by the wallet’s compactness. A mitigation is to place your most frequently accessed items on either side of the stack, such that frequently used items can be removed and replaced without having to remove the stack.
***
The Compact Wallet is a skunk-works project. The documentation above—the Traceability Matrix, DFMEA, and V&V test Plan (not shown)—represent critical product development tools. In actual product development, these engineering documents have several additional columns and usually a few hundred rows. The inputs include the collective intelligence of the full product development team.
I am currently developing a follow-up post explaining how this data can be assembled into a KG-RAG (Knowledge Graph – Retrieval Augmented Generation) agent. My goal is not to turn the agent over to an AI, but to use an LLM as ‘Augmented Intellegence,’ an additional team member with the ability to quickly recall all inputs as well as any regulation or guidence document that may seem relevent.
Engineered Products, GD Consulting’s “garage” division, aspires to discover, design, and develop worthwhile widgets. See also: The ITK, Innovation Toolkit– My “low-tech” survival kit for the AI age.
Glenn DiCostanzo, April 2026